Electric pliers



1964 1-:. c. KOLTERMAN 3,120,549

ELECTRIC PLIERS Filed Oct. 12, 1961 mmvrox. 176. 4. EDh/l/V 6. KOLTE/PMA/V ATTORNEYS United States Patent 3,120,649 ELECTRIC PLIERS Edwin C. Kolterman, Boulder, Colo., assignor to Poudre Products Co., Inc., Fort Collins, Colo, a corporation of Colorado Filed Oct. 12, 1961, Ser. No. 144,683 3 Claims. (Cl. 336180) This invention relates broadly to electric heating devices and more particularly to such devices which may be used to heat sweat joints and the like to effect a soldered joint between pipe and pipe fittings which may conveniently be of copper and like metals.

With the advent of modern building practices for residential as well as commercial building, the trend is to install copper plumbing for longer life and a more serviceable installation. In recent years, the use of sweat joint construction has been increasingly used due in part to the ease and economy realized in this type of installation over a threaded pipe installation. Several disadvantages are encountered in a sweat joint installation since it is usual to rely upon a gasoline or propane torch for the heating step. A considerable fire hazard is presented while working in close quarters with wooden floor joists and other structural members which requires great care on the part of the workman to avoid igniting the structure. This extra care consumes a considerable portion of the workmans time resulting in a greater expense to the ultimate homeowner. In addition, the application of flame heat to the sweat joints suffers in being non-uniform with a fairly high occurence of joint failure.

It is an object of the present invention to provide a new and improved arrangement for electrically heating a sweat joint and the like which substantially avoids one or more of the limitations of prior art arrangements.

- 'It is a principle object of the present invention to provide an improved arrangement for heating sweat joints and the like which is safe, economical and effective.

A further object of the present invention is to provide an improved electrical arrangement for heating sweat joints and the like which is eflicient, highly portable, attractive in appearance and operative from ordinary house current.

A still further object of the present invention is to pro vide an improved arrangement for heating sweat joints and the like which provides uniform heating of the joint, will handle large diameter joints yet is of minimal size.

Another object of the invention is to provide an improved transformer means for use with an electrical arrangement suited to heat sweat joints which transformer provides a maximum power transfer to a work piece While operating within safe temperature limits and without burnout failure as is usual with such prior art devices.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the drawing:

FIGURE 1 is a view in elevation, partially schematic, of the improved transformer according to the instant invention;

FIGURE 2 is a diagramatic representation of the improved transformer according to the invention;

IFIGURE 3 is a plan view of the arrangement according to the invention showing the transformer Working electrodes and connecting cables;

FIGURE 4 is a view in elevation, partly in section and partly broken away to conserve space, of the connecting cable terminal of the working electrodes and the mating socket of the transformer; and,

FIGURE 5 is a cross-sectional view of a portion of the 3,120,649 Patented Feb. 4, 1964 secondary windings of the transformer according to the present invention.

Referring now to FIGURES l, 2 and 3, the heating arrangement of the present invention comprises in combination, a transformer 10 having a primary winding 12 adapted to be connected to a source of electrical power via conductors 14 and 16. The primary winding is provided with a tap 18 connected via conductor 20 to one contact 22 of a single pole-double throw switch 24. An end of the primary 12 is connected via conductor 26 to the other contact 28 of switch 24. When the pole of switch 24 is in contact respectively with contact 22 or 28, the transformer is connected to the power source for respectively high or low power operation. The secondary windings of transformer 10! are connected via conductors 30 and 32 to a'clamp device 34 comprising a pair of contacts 36 and 38 hingedly connected as at for pivotal movement with respect to each other. Contacts 36 and 3-8 may conveniently be provided with low resistance material such as carbon for efiicient electrical contact with a workpiece. In use, the primary of transformer 10 is connected to a source of electrical power and the contacts 36 and 33 of clamp device 34 are positioned to either side in diametrically opposed relation of a pipe fitting of the sweat joint variety. The arrangement of the invention is a low voltage-high current device and the current which flows between contacts 36 and 38 through the fitting develops heat therein due to the electrical resistance thereof to the passage of current therethrough sufficient to raise the temperature of the fitting quickly to a soldering temperature. Due to the high efficiency of the arrangement of the invention, it has been possible to fabricate a unit which will solder through three inch copper pipe in approximately one minute, yet weighs a total of only 26 pounds.

The configuration and construction of the transformer 19 and the manner of connecting the secondary winding thereof accounts in large measure for the success and efliciency of the instant invention. A result has been achieved which was not heretofore thought possible without an excessively large and cumbersome transformer or one which would not supply adequate power without overheating and burnout.

The material of core 11 used in the transformer 10 is a magnetic material and is preferably permanently magnetized, such as for example a material identified as L-lO, M19, 24g. A specific example of a transformer according to the invention has a primary winding 12 of three hundred turns of number twelve round insulated wire connected to a power source via conductors 14 and 16 of number eighteen wire. The conductors, 14 and 1 6, are preferably of a smaller wire size than the primary winding for the reason to be explained as the description proceeds. A tap is made at fifty turns of the primary winding for use in the high power operation. The secondary winding 4-2 comprises fifteen turns of bifilar wound glass coated wire having a rectangular cross-section of 0.029 inch by 0.110 inch. Each layer of the secondary winding is offset with respect to the adjacent layer as best seen in FIG- URE 5. As seen in FIGURE 2, the secondary can be considered to be made up of legs 44, 46, 48 and 50. Legs 4-4 and 46 are wound together as layers one and two and legs 48 and are wound together as layers three and four. -It will be seen that legs 44 and 46 are in series with each other and are connected in parallel with legs 48 and 50 which are in series. A layer of suitable insulation is provided between the primary winding and the secondary winding, and between the layers of the secondary winding. The common junction of legs 44 and 48 of secondary wind-ing 42 is connected to one output terminal 52 of transformer 10 via conductor 54 and the common junction of legs 46 and 56 are connected to another output terminal 5 6 via conductor 58. With a power source of 115 volts, 60 cycle current the following data was taken with the above example based on zero contact resistance and an ambient temperature of 25 C.:

Table 1 Low High Total Power in" 2. 9 3. 45 Total Power out." 940 1, 370 Etficienoy percent 32. 5 40. Effective Resistance:

Primary and Power Cord ol1ms O. 420 0. 366

Secondary and Cablc do 0. 007 0.000 Effective Primary Volts -v 104. 5 104. 7 Primary Current mps Primary Power Loss. watts 260 330 Eficctive Secondary Volts v 3. 25 3. Secondary Volts (no load). v 8. 9 10. 3 Secondary Amps. (1 iron pipe) amps. 465 500 Secondary Power Loss "watts" 1, 700 1, 750

It was found that the use of smaller size wire in the power cord than that used in the primary winding provided a means of preventing a run away condition. If the same wire size or larger wire were used as in the prirnary winding, the danger of exceeding the electrical limits of the transformer is greatly increased. Apparently a measure of current limiting is provided by the smaller size wire and a more even distribution of power loss is achieved which serves to avoid hot spots either in the cable or in the transformer for greater life and etliciency.

As best seen in FIGURE 4, conductor 30 is formed as part of an insulated cable and is provided with a. suitable contact 62 of tapered con-figuration. Terminal 52 of transformer 10 is mounted in an enclosing case 64 for the transformer and insulated therefrom by an insulating sleeve 66. The external portion of terminal 52 is provided with a plurality of heat conducting fins 68 and is secured in position on sleeve 66 by nut 70.

It is intended that the previous example is for illustration only and the invention is not intended to be limited thereby. While there has been described what at present is considered to be the preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein Without departing from the invention. It is aimed, therefore, in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention,

What is claimed is:

1. An electric heating arrangement for use in heating sweat joints and the like, comprising in combination a transformer having a primary winding adapted to be connected to an electric power source, means connecting the primary of said transformer to the power source, said transformer having a secondary winding with a substantially smaller number of turns than the primary to provide an output therefrom of a substantially lower voltage than the power source at high current, said secondary winding being multi-layered and comprised of bifilar wound insulated conductor of rectangular cross-section with onehalf of the b'iiilar wound secondary being electrically connected in series aiding relation with the other half and the output of the transformer being adapted to be connected to a work-piece to be heated wherein the con ductors of one layer of the secondary winding of the transformer are offset with respect to superposed conductors of adjacent layers thereof.

2. A transformer for use in an electrical arrangement of the class describe-d comprising a magnetic core, a primary Winding on said core adapted to be connected to a source of electrical power and a secondary winding with a substantially smaller number of turns than the primary to provide an output therefrom of a substantially lower voltage than the power source at high current, said secondary being comprised of bifilar wound insulated con ductor of rectangular cross-section with one half of the bi-filar wound secondary being superposed on and electrically connected in series aiding relation with the other half.

3. A transformer as set forth in claim 2 wherein the core is permanently magnetized.

References Cited in the file of this patent UNITED STATES PATENTS 1,382,905 Gravell June 28, 1921 1,734,913 Norman Nov. 5, 1929 1,913,575 Vollmar June 13, 1933 2,426,985 Darmara Sept. 9, 1947 2,556,602 Schwartz June 12, 1951 2,828,405 Morrison Mar. 25, 1958 2,838,740 Larky et al. June 10, 1958 2,988,723 Archer June 13, 1961 FOREIGN PATENTS 854,564 Great Britain Nov. 23, 1960 

1. AN ELECTRIC HEATING ARRANGEMENT FOR USE IN HEATING SWEAT JOINTS AND THE LIKE, COMPRISING IN COMBINATION A TRANSFORMER HAVING A PRIMARY WINDING ADAPTED TO BE CONNECTED TO AN ELECTRIC POWER SOURCE, MEANS CONNECTING THE PRIMARY OF SAID TRANSFORMER TO THE POWER SOURCE, SAID TRANSFORMER HAVING A SECONDARY WINDING WITH A SUBSTANTIALLY SMALLER NUMBER OF TURNS THAN THE PRIMARY TO PROVIDE AN OUTPUT THEREFROM OF A SUBSTANTIALLY LOWER VOLTAGE THAN THE POWER SOURCE AT HIGH CURRENT, SAID SECONDARY WINDING BEING MULTI-LAYERED AND COMPRISED OF BIFILAR WOUND INSULATED CONDUCTOR OF RECTANGULAR CROSS-SECTION WITH ONEHALF OF THE BIFILAR WOULD SECONDARY BEING ELECTRICALLY CONNECTED IN SERIES AIDING RELATION WITH THE OTHER HALF AND THE OUTPUT OF THE TRANSFORMER BEING ADAPTED TO BE CONNECTED TO A WORK-PIECE TO BE HEATED WHEREIN THE CONDUCTORS OF ONE LAYER OF THE SECONDARY WINDING OF THE TRANSFORMER ARE OFFSET WITH RESPECT TO SUPERPOSED CONDUCTORS OF ADJACENT LAYERS THEREOF. 